tive in producing activation, further supporting the hypothesis of Schiff-base formation for which a terminal primary amine group is required. I t is hoped that results of these studies may provide fur- ther information concerning the metabolism of dopamine and nor- epinephrine in terms of endogenous aldehyde levels and agents that alter these levels.

REFERENCES

(1) G. Cohen and M. Collins, Science, 167,1749(1970). (2) V. E. Davis and M. J. Walsh, ibid., 167,1005(1970). (3) M. Sandler, S. B. Carter, K. R. Hunter, and G. M. Stern,

Nature, 241,439(1973).

(4) H. C. Sabelli and W. J. Giardina, Biol. Psychiat., 2, 119( 1970).

(5) A. C. Collins, V. E. Davis, and J. Cashaw, Abstracts for the Third Meeting of the American Society for Neurochemistry, Seat- tle, Wash., Mar. 1972, p. 66.

(6) J. Axelrod and R. Tomchick, J . Biol. Chem., 233,702(1958). (7) J. Axelrod and E. S. Vesell, Mol. Pharmacol., 6,78(1970).

ACKNOWLEDGMENTS AND ADDRESSES

Received January 14, 1974, from Texas Research Insti tute of

Accepted for publication March 28,1974. T o whom inquiries should be directed.

Mental Sciences, Houston, T X 77025

Synthesis and Screening of Potential Antimalarial Agent a-( 2-Piperidyl)-2-( l-adamantyl)-6,8-dichloro-4-quinolinemethanol Hydrochloride

JAROSLAV NOVOTNY, CAROL H. COLLINS, and FRED W. STARKSx

Abstract 0 The synthesis and biological testing of a-(Z-piperidyl)- 2-(l-adamantyl)-6,8-dichloro-4-quinolinemethanol hydrochloride and its 0-acetyl and N-acetyl derivatives are reported. Direct hy- drogenation of the cu-pyridyl ketone gave very low yields. A novel procedure was developed which permits formation of piperidyl quinolinemethanols in satisfactory yields.

Keyphrases 0 n-(2-Piperidyl)-2-(l-adamantyl)-6,8-dichloro-4- quinolinemethanol hydrochloride (and N-acetyl and 0-acetyl de- rivatives)-synthesized and screened as potential antimalarial agents 0 Quinolinemethanols, n-(2-piperidyl) analog and N-acetyl and 0-acetyl derivatives-synthesized and screened as potential antimalarial agents 0 Antimalarial agents, potential-synthesis and screening of m-(2-piperidyl)-2-(l-adamantyl)-6,8-dichloro-4- quinolinemethanol hydrochloride and N-acetyl and 0-acetyl de- rivatives

Antimalarial activity has been reported for many derivatives of the quinine analog 4-quinolinemetha- nol. Mono- or disubstitutions a t the 6-, 7-, or 8-posi- tion of the quinoline nucleus enhance activity rela- tive to the unsubstituted compound, while substitu- tion at the 2-position appears necessary to retard metabolic oxidation of the quinoline skeleton (1-4).

Unfortunately, the more active 2-aryl-4-quino- linemethanols also have undesirably high phototoxic-

ROCHR

10: R = H, R = CH,N( C,H,), Ib: R = H, R’=e-piperidyl Ic: R = H, R = N-acetyl-2-piperidyl Id: R =CH,,CO, R’ = 2-piperidyl

ity, which might detract from their use as antimalar- ial agents in humans (3, 5-8). Recently, a number of 4-quinolinemethanols were prepared with nonaryl substitution a t the 2-position (9-11). Mixed results indicated further search for appropriate substitution a t this position. Use of an adamantyl substituent at position 2 was suggested by the enhanced biological activity of this substituent in comparison to more conventional saturated moieties in other medicinal agents (12-14). Synthesis of several 2-adamantylqui- nolinemethanols has been reported (15). The promis- ing antimalarial activity of a-(di-n-butylamino- methyl) -2-( l-adamantyl)-6,8-dichloro-4-quinolineme- thanol (Ia) (15) suggested that the cu-(2-piperidyl) analog (Ib) should be synthesized and tested.

The synthesis and biological screening of a-(2- piperidyl) -2-( 1-adamantyl) -6,8-dichloro-4-quinoline- methanol (Ib) as well as the related N-acetyl (Ic) and 0-acetyl (Id) derivatives are reported here. Prepara- tion of (Id) was necessitated when the usual selective catalytic hydrogenation of the pyridyl ketone (4, 16) produced the desired product in very small yields. The modification, a two-step reduction, permits good yields of the a-2-piperidyl-4-quinolinemethanol ( I b ) .

CHEMISTRY

Compound Ib was prepared as illustrated in Scheme I. Acetylad- amantane (11) (17, 18) was obtained in 59% yield, by the method of Tegner (19), from the addition of methyllithium to adamantane- I-carboxylic acid followed by hydrolysis. A by-product of this reac- tion, Z-(l-adamantyl)propan-2-ol (20), was also isolated in low yield (about 4%). The formation of this product was somewhat sur- prising, because Tegner (19) suggested that methyllithium should not react further with the dilithium salt of the ketone, even though phenyllithium has been shown to give tertiary alcohols in its reac- tion with carboxylic acids and their derivatives (21).

1264 /Journal of Pharmaceutical Sciences

In this study, the Pfitzinger (22) condensation of 5,7-dichlo- roisatin and I1 produced the cinchoninic acid (111) (15) in 48% yield. Slow addition of I11 to a-pyridyllithium (23, 24) a t -74' fol- lowed by hydrolysis gave pyridyl ketone (IV) in 84% yield. When this reaction was carried out at -60°, according to literature direc- tions (4), the yield was only 46%.

When the one-step selective hydrogenation (4, 16) of IV to Ib was attempted, the desired compound was obtained in only 4% yield. This occurred in conjunction with a theoretical absorption of hydrogen. Similar low product yields and the formation of side- products have been reported in the selective hydrogenation of sev- eral other 2-pyridyl quinolyl ketones that lacked a 2-aryl substitu- ent (10 , l l ) .

A satisfactory yield of Ib ensued by first reducing the carbonyl with sodium borohydride (99% yield), acetylating the carbinol (60%), hydrogenating this (59%), and, finally, hydrolyzing the re- duced 0-acetyl compound (Id) in 52% yield. Compound Id hydro- lyzed smoothly to Ib in either sodium methoxide or concentrated hydrochloric acid. However, in ammonium hydroxide a t room tem- perature, the acetyl group migrated to the piperidyl nitrogen. The molecular arrangement of the piperidyl nitrogen and methanol oxygen made probable the facile formation of a six-membered ring as an intermediate in this intramolecular migration under the mild conditions employed. Use of stronger reagents hydrolyzes either the N-acetyl or the 0-acetyl compound.

BIOLOGICAL ACTIVITY

Compound Ib and the several intermediates were tested' for an- timalarial activity against Plasmodium berghei in mice and against P. gallinaceurn in chicks. Assessment of activity was based on the influence of various doses of the compounds upon the sur- vival times of groups of mice in comparison with untreated con- trols (mean survival time 6.2 days). Those surviving more than 60 days were adjudged "cured." Compound Ib was active a t the 320- mg/kg level against P. berghei, effecting two (out of five) cures a t this level. None of the other compounds (Ic, Id, IV, V, and VI) showed antimalarial activity (Table I).

Compounds Id, Ic, and Ib were also evaluated against blood-in- duced P. gallinaceum infections in chicks (25)'. They showed no significant activity. A similar response to P. berghei and P. galli- naceum has been reported for the di-n-butylaminomethyl analog (10) (15).

EXPERIMENTAL*

1-Acetyladamantane (11)-In a modification of the method of Tegner (19), an excess of methyllithium (2 M in ether) was added dropwise to a stirred solution of 721 g (4.0 moles) of adamantane- 1-rarhoxylic acid3 in 6 liters of ether, maintained under nitrogen at from -10 to 0" by partial immersion in a dry ice-acetone bath. The mixture was stirred at room temperature for 1 hr and then hy- drolyzed by dropwise addition of wet ether followed by water. The organic layer was separated, washed with water, and dried (magne- sium sulfate). The solvent was evaporated in uucuo and the crude product was recrystallized from methanol t o give 420 g (59%) of analytically pure material, mp 51-53' [lit. (17, 18) mp 53-54']. The product was homogeneous to VPC with a retention time of 14.2 min.

Anal.-Calc. for C12H180: C, 80.85; H, 10.18; 0, 8.97. Found: C, 80.62; H, 10.18; 0,9.16.

2-( l-Adamantyl)propan-2-ol-The mother liquor from recrys- tallization of crude 1-acetyladamantane was spin evaporated to an

I By Dr. L. Rane of the Malaria Screening Laboratory, University of Miami ( 2 5 ) . The test results were provided by the Walter Reed Army Insti- tute o f Research through the courtesy of Dr. T. R. Sweeney and Dr. B. T. Poon.

Melting points were determined on a Fisher-Jones apparatus. Those below 230' are corrected. Elemental analyses were performed by Galbraith Laboratories, Inc., Knoxville, Tenn. UV spectra were determined in ethanol with a Bausch and Lomb Spectronic 505 spectrophotometer. TLC was run on Eastman silica gel chromagram sheets 6060, using a t least three different solvent systems for each compound. Vapor phase chromatography (VPC) was carried out using a Hewlett-Packard model 5750B. temperature pro- grammed at 10"/min from 40 to 250°, using a 2-m X 3-mm column packed with 10% UC-W982 on 80-100-mesh Diatoport S.

Aldrich Chemical Co.

Table I-Antimalarial Activity in Blood-Induced Infections

Increase in Survival Time, D a y s

Evaluat ion against

P. gallinaceurn B r u m p t 8A i n

Dose, Noninbred I C R / H A Whi te Leghorn

P . berghei KBG

m d k g Swiss Micea Chicksn

Malar ia i n Young 9-12-day-old

I b ~

Id Ib 10 0 . 3 20 0 . 3 0 . 3 0 .1 0 . 0 40 0 . 5 0 .3 0 . 3 0 .o 80 0 . 5 0 5 0 3 0 .o - . _ . ..

160 i : i i19 0 .7 0 .o 320 2/5Cb 1 . 9 0 .o 640 2/5Cb 5 . 9 3 . 4

The test results were provided by the Walter Reed Army Institute of Research through the courtesy of Dr. T. R. Sweeney and Dr. B. T. Poon. * C = curm, the number of mice surviving 60 days after infection.

oil which was distilled (bp 65-67'/10 mm). An analytically pure product was obtained by crystallization from aqueous ethanol, mp 65-67' [lit. (20) mp 77-80']. The product was homogeneous to VPC with a retention time of 14.8 min and was identical to a sam- ple synthesized independently from methylmagnesium iodide and acetyladamantane.

Anal.-Calc. for C13H220: C, 80.36; H, 11.41. Found: C, 80.45; H, 11.50.

6,8-Dichloro-2-( 1-adamanty1)cinchoninic Acid (111)-A mixture of 178 g (1.00 mole) of 11, 197 g (0.910 mole) of 5,7-dichlo- roisatin3, 1 liter of ethanol, 340 ml of water, and 161 g (2.90 moles) of potassium hydroxide was refluxed for 17 hr, cooled, and then evaporated in uacuo to a residue (22). The residue was partitioned between water and ether. The aqueous layer was separated, washed with ether, and then acidified by addition of concentrated hydrochloric acid to precipitate the product. The solid was collect- ed, washed by resuspension in hot ethanol, dried, and recrystal- lized from acetone to yield 166 g (48%), mp 260-263O dec. [lit. (15) mp 258-261'1; Amax (c X 241 (29.0), 298 (4.6), and 332 (4.6) nm.

And-Calc. for C20H19ClZN02: C, 63.84; H, 5.09; N, 3.72. Found: C, 64.07; H, 5.05; N, 3.68. 2-Pyridyl-2-(l-adamantyl)-6,8-dichloro-4-quinolyl Ketone

(W-An ethereal solution of 2-pyridyllithium was prepared, ac- cording to the method of Wibaut et 01. (23), from 166 g (1.05 moles) of 2-bromopyridine, 1000 ml of ether, and 425 g (1.00 mole) of a 15% solution of n-butyllithium in hexane. While maintaining the nitrogen atmosphere, the ethereal solution was cooled to -74' and 125 g (0.333 mole) of I11 was added portionwise over 1.25 hr. After the addition, the mixture was stirred for 1 hr at -73", for 1 hr a t between -70 and -68O, for 1 hr at between -68 and -63', and for 1 hr between -63 and -59'. After warming slowly to lo', 500 ml of water was cautiously added. After separating the layers, the aqueous portion was extracted several times with ether. The combined ether solution was dried (magnesium sulfate) and the solvent was removed in uacuo. The residue was triturated with ethanol to yield crude product, which was recrystallized from etha- nol, yielding 122 g (84%), mp 138-140°, homogeneous to TLC; A,,, (c X

Anal.-Calc. for C ~ J H Z ~ C ~ ~ N ~ O : C, 68.66; H, 5.07; C1, 16.21; N, 6.40. Found: C, 68.60; H, 5.24; C1, 16.06; N, 6.60.

a-(2-Pyridyl)-2-( l-adamantyl)-6,8-dichloro-4-quinoline- methanol (V)-Sodium borohydride (51.3 g, 1.35 moles) was added portionwise to a stirred solution of 593 g (1.35 moles) of IV in 9 liters of ethanol. The mixture was stirred overnight a t room temperature. The solvent was removed in uacuo and the residue was dissolved in chloroform, which was then washed with water, dried (magnesium sulfate), and removed by spin evaporation in uacuo. The residue was recrystallized from methanol to give 587 g (99%) of product, pure to TLC (four systems), mp 177-177.5'; Amax ( 6 X 238 (31.2), 262 (4.3), 268 (4.3), 284 (4.2), 316 (2.2), and 330 (2.3) nm.

232 (38.6) and 332 (4.0) nm.

Vol. 63, No. 8, August 1974 / 1265

COIH

, H\ C H C 0 0 C H

.HCl

V IV

Id NH,-CH,@H J Y

n n

I C

Scheme I Ib

And-Calc. for C25H24C12N20: C, 68.34; H , 5.51; C1, 16.14; N, 6.38. Found: C, 68.38; H, 5.36; CI, 16.10; N, 6.23. a-( O-Acetyl)-a-(2-pyridyl)-2-( l-adamantyl)-6,8-dichloro-4-

quinolinemethanol (V1)-A solution of 461 g (1.05 moles) of V in 1690 ml of acetic anhydride was heated at approximately 100' for 15 min. While still hot, the excess acetic anhydride was hydrolyzed with water. After cooling, the reaction mixture was poured into ad- ditional water. The white solid that separated was collected, washed with water, and recrystallized from ethanol to give 303 g (60% yield) of pure product (TLC), mp 174-175'; A,,, (6 X lo-"): 240 (48.2). 268 (6.3), 286 (6.4), 319 (3.7), and 333 (3.8) nm.

Anal.-Calc. for C ~ ~ H ~ G C I ~ N ~ O ~ : C, 67.36; H, 5.44; C1, 14.72; N, .5.81; 0, 6.64. Found: C, 67.44; H, 5.47; CI, 14.83; N, 5.83; 0, 6.69. a-( O-Acetyl)-a-(2-piperidyl)-2-( l-adamantyl)-6,8-dichloro-

4-quinolinemethanol Hydrochloride (Id-HC1)-A mixture of 71.2 g (0.148 mole) of VI, 900 ml of absolute ethanol, 25 ml of con- centrated hydrochloric acid, and 0.8 g of platinum oxide was hy- drogenated at 50 psi until the theoretical amount of hydrogen (3 moles) had been consumed (4 hr). The resulting suspension was dissolved in 1700 ml of absolute ethanol and filtered through a dia- tomaceous earth4 pad. The filtrate and washings were concentrat- ed in UQCUO to give a crude product, which was recrystallized from absolute ethanol to give 42 g (59%) of pure product (TLC), mp 205.5-207.5' dec.; A,,, (6 X lo-"): 239 (55.1), 285 (5.8), 320 (3.6), and 334 (3.7) nm.

Anal.-Calc. for C Z ~ H ~ ~ C I ~ N ~ O ~ : C, 61.90; H, 6.35; CI, 20.32; N,

1 Celite.

1266 /Journal of Pharmaceutical Sciences

5.35; 0, 6.11. Found: C, 61.83; H, 6.43; C1, 20.13; N, 5.26; 0,6.07. a-[2-( I-Acetylpiperidy1)l- 2-( 1-adamanty1)- 6,s-dichloro- 4-

quinolinemethanol (1c)-Dry methanol (1000 ml), saturated with ammonia a t 0", was added to 10.0 g (0.0'20 mole) of solid Id- HCI a t 0'. The mixture was kept a t Oo overnight. Volatiles were re- moved by spin evaporation in oucuo, and the resulting solid was dissolved in 500 ml of chloroform. This solution was washed with water, dried (magnesium sulfate), and concentrated in uucuo to give a crude product, which was recrystallized from methanol to yield 4.4 g (44%), mp 246-249', pure to TLC; A,,, (6 X lo-"): 238 (46.7), 285 (6.0), 317 (3.1), and 331 (3.1) nm.

And-Calc. for C ~ ~ H ~ ~ C I ~ N Z O ~ : C, 64.41; H, 6.41; CI, 14.08; N, 5.56; 0, 9.53. Found: C, 64.35; H, 6.51; CI, 14.19; N, 5.51; 0,9.22.

a-(2-Piperidyl)- 2-( 1-adamanty1)- 6,8-dichloro-4-quinoline- methanol Hydrochloride (Ib-HC1)-A solution of 237 g (0.487 mole) of Id-HCI in 2370 ml of concentrated hydrochloric acid was refluxed overnight, cooled to 15", and neutralized to pH 12 with 33% aqueous sodium hydroxide. The white precipitate was collect- ed, washed with water, and then dissolved in 20 liters of chloro- form. The solution was dried (magnesium sulfate) and then satu- rated with 230 g (16.3 moles) of anhydrous hydrogen chloride. The white solid was filtered, washed with ether, and dried before being dissolved in 38 liters of ethanol containing 45 ml of concentrated hydrochloric acid. The solution was filtered hot, and the filtrate was reduced in volume to about 5.5 liters. The product crystallized on cooling to yield 122 g (52%) of material pure to TLC, mp 253- 255' dec.; A,,, ( c X lo-"): 237 (46.5), 283 (5.8), 317 (3.1), and 330 (3.4) nm.

Anal.-Calc. for C ~ ~ H ~ I C I ~ N ~ O : C, 62.31; H , 6.48; C1, 22.07; N,

5.81. Found: C, 62.15; H, 6.70; C1,21.80; N, 5.67. An identical product was obtained by treating 10 g of Id-HCI

with 40 ml of a 1 M solution of sodium methoxide in 1000 ml of dry methanol.

REFERENCES

( 1 ) R. E. Lutz, P. S. Bailey, M. T. Clark, J. F. Codington, A. J. Deinet, J. A. Freck, G. H. Harnest, N. H. Leake, T. A. Martin, R. J. Rowlett, Jr., J. M. Salsbury, N. H. Shearer, Jr., J. D. Smith, and J . W. Wilson, 111, J. Arner. Chern. SOC., 68,1813(1946).

(2) J. Mead and J. B. Koepfli, J. Biol. Chem., 154,507(1944). (3) J . P. Schaefer, K. S. Kulkarni, R. Costin, J. Higgins, and L.

(4) D. W. Boykin, Jr., A. R. Patel, and R. E. Lutz, J . Med.

(5) W. E. Rothe and D. P. Jacobus, ibid., 11,366(1968). (6) I. G. Fels, ibid., 11,887(1968). (7) E. R. Atkinson and A. J. Puttick, ibid., 13,537(1970). (8) Ibid., 11, 1223(1968). (9) R. M. Pinder and A. Burger, J. Med. Chern., 11,267(1968).

(10) A. R. Patel, C. J. Ohnmacht, D. P. Clifford, A. S. Crosby,

(11) C. J . Ohnmacht, A. R. Patel, and R. E. Lutz, ibid., 14,

(12) K. Gerson and D. Kau, ibid., 10,189(1967). (13) A. N. Voldeng, C. A. Bradley, R. D. Kee, E. L. King, and F.

(14) V. L. Narayana, J. Med. Chern., 15,1180(1972). (15) R. B. Fugitt and R. M. Roberts, ibid., 16,875(1973). (16) D. W. Boykin, Jr., A. R. Patel, R. E. Lutz, and A. Burger, J.

M. Honig, J. Heterocycl. Chem., 7,607(1970).

Chem., 11,273(1968).

and R. E. Lutz, ibid., 14, 198(1971).

926(1971).

L. Melder, J . Pharm. Sci., 57,1053(1968).

Heterocycl. Chern., 4,459(1967). (17) H. Stetter and E. Raucher, Chern. Ber., 93,2054(1960). (18) S. Hala and S. Landa, Collect. Czech. Chem. Commun., 25,

(19) C. Tegner, Acta Chern. Scand., 6,782(1952). (20) E. C. Hermann and J. A. Snyder (to E. I. duPont de Nem-

ours and Co.), US. pat. 3,284,445 (Nov. 8, 1966); through Chern. Abstr., 66,28760(1967).

(21) H. Gilman and P. R. van Ess, d. Amer. Chern. SOC., 55, 1258( 1933).

(22) W. Pfitzinger, J. Prakt. Chem., 56, 383(1897); cf., H. G. Lindwall, J . Bancles, and I. Weinberg, J . Amer. Chern. Soc., 53, 317(1931).

(23) J. P. Wibaut, A. P. de Jonge, H. G. P. Van der Voort, and P. P. H. L. Otto,Rec. Trau. Chin., 70,1054(1951).

(24) H. Gilman and S . M. Spatz, J. Arner. Chern. Soc., 62, 446(1940).

(25) T. S. Osdene, P. B. Russell, and L. Rane, J. Med. Chem., 10,431(1967).

2692( 1960).

ACKNOWLEDGMENTS AND ADDRESSES

Received January 4, 1974, from Starks Associates, Inc., Buffalo,

Accepted for publication March 27, 1974. Supported by the U S . Army Medical Research and Develop-

ment Command under Contract DA-49-193-MD-2751. This is Contribution No. 1174 of the Army Research Program on Malaria.

The authors thank Mr. Bruce Mayer, Mr. Walter Schreiner, and Mrs. Anita White for their valuable contributions to the synthetic work.

N Y 14213

To whom inquiries should be directed.

Binding of Qumidine to a Red Blood Cell Hemolysate Preparation

V. E. ISAACS* and R. D. SCHOENWALD"

Abstract 0 A constant degree of binding of quinidine to a red blood cell hemolysate preparation was found for a clinically sig- nificant range of concentrations at 37" using the methods of equi- librium dialysis and ultracentrifugation. By repeating the binding experiments a t 37" but over a much wider range of quinidine con- centrations, it was possible to calculate an association constant (252 liters/mole) and the apparent number of binding sites (1.54). Quinidine appeared to be bound to a single binding site. In an- other series of experiments performed at therapeutic levels and 37". the competitive binding of quinidine was studied in the pres- ence of red blood cell hemolysate and serum, each placed in indi-

vidual compartments of a dialysis cell but separated by a semi- permeable membrane. Following attainment of equilibrium, free drug was separated from bound drug by ultracentrifugation. Cal- culations indicated that slightly more than half of the drug was contained within the serum compartment. Keyphrases 0 Quinidine-binding to a red blood cell hemolysate preparation, influence on protein binding of quinidine, binding parameters 0 Binding-quinidine to a red blood cell hemolysate preparation, influence on protein binding of quinidine Erythro- cyte binding-quinidine to a red blood cell hemolysate prepara- tion, binding parameters

Quinidine has been shown to interact with various proteins contained within the body's vascular pool. For example, elucidation of a quantitative quinidine- albumin relationship a t pH 7.4 established the exis- tence of one receptor location on an albumin mole- cule and an association constant of 7.7 x lo3 (1). There is also extensive binding of quinidine to human platelets as evidenced by its large accumula- tion within the platelet, much greater than would be expected on the basis of pH partitioning (2). More-

over, quinidine has been found to penetrate red blood cells (3), which might be expected to occur for an organic base with a pKa of 8.6 (4) whose unio- nized form is lipid soluble (5). Because of its potential for binding, the purposes of this study were to deter- mine the binding affinity of quinidine to a n eryt hro- cytic preparation obtained from freshly drawn human blood samples and to determine its competi- tive influence on the protein binding of quinidine in human serum.

Vol. 63, No. 8, August 1974 / 1267